Whale Safe Impact

Author

Emily Nazario

Published

April 7, 2025

Voluntary Vessel Speed Reduction (VSR) Zone & Whale Safe background

VSR data notes

San Francisco data does not include the Monterey Bay National Marine Sanctuary, which was added to the VSR program in 2023. The Whale Safe system that was launched in San Francisco was designed to give whale presence in the San Francisco portion of the VSR zones so we are reporting on them separately here for now. The Monterey Bay stats come from a different data pipeline and the offseason stats are not tracked as regularly.

Whale Safe System Launch Dates

Southern California: September 17, 2020

San Francisco: September 21, 2022

Vessel Speed Reduction Zones

Vessel Speed Reduction Season Dates:

Southern California:

  • June 4 - December 31, 2018:

  • May 15 - December 15, 2019

  • May 15 - December 15, 2020

  • May 15 - December 15, 2021

  • May 1 - December 15, 2022

  • May 1 - December 15, 2023

  • May 1 , 2024 - January 15, 2025

San Francisco

  • May 1 - November 15, 2019

  • May 1 - November 15, 2020

  • May 1 - November 15, 2021

  • May 1 - December 15, 2022

  • May 1 - December 15, 2023

  • May 1 , 2024 - January 15, 2025

WPR data notes

Blue whale model data might have been retroactively filled in after periods where the server was down. We don’t have this tracked in our data so there may be days where the Whale Presence Rating didn’t take the blue whale model value into account.

Each species has a threshold for each data stream see Methodology for what is considered low-high (0-1). The Whale Presence Rating considers the highest rating of any of the data streams over 5 days. Two species need to have a high rating in order for the overall Whale Presence Rating to be ‘Very High’.

Vessel compliance/cooperation level

Cooperation time series w.r.t. VSR status

Time series grouped by region where grey shaded bars represent time periods when the VSR zone in each respective region was active. Points represent year-month averages pooled across vessel types for each region.

Cooperation table: Zone x Ship category

Table displaying % cooperation grouped by region and ship category. Values in the active and inactive columns represent cooperation by VSR status, and the final column represents the change in cooperation between periods when the VSR is active vs. inactive.

Ship category VSR active cooperation (%) VSR inactive cooperation (%) Change (%)
Monterey Bay
bulk 56.41516 NA NA
container 71.99507 NA NA
fishing 79.73571 NA NA
general cargo 39.58673 NA NA
other industry 60.00006 NA NA
passenger 48.09752 NA NA
pleasure 24.63185 NA NA
research 76.55128 NA NA
ro-ro 65.13670 NA NA
tanker 62.00351 NA NA
towing/pushing 79.52811 NA NA
San Francisco
bulk 58.13379 37.811502 -20.3222859
container 67.63435 30.487235 -37.1471159
fishing 25.61000 84.623333 59.0133333
general cargo 44.29325 36.075447 -8.2178062
other industry 51.94873 56.620221 4.6714908
passenger 48.72211 18.802619 -29.9194954
pleasure 10.21415 6.872143 -3.3420035
research 64.79967 52.764328 -12.0353416
ro-ro 69.32563 37.090640 -32.2349914
tanker 65.69202 35.694435 -29.9975856
towing/pushing 79.18797 74.009009 -5.1789630
Southern California
bulk 70.07931 60.473503 -9.6058060
container 75.66559 57.991820 -17.6737659
fishing 72.28187 65.010526 -7.2713487
general cargo 59.09313 58.628251 -0.4648776
other industry 71.31535 74.017635 2.7022831
passenger 45.43029 48.072736 2.6424482
pleasure 39.04593 25.476143 -13.5697918
research 54.37780 54.831314 0.4535181
ro-ro 75.00277 47.438869 -27.5638977
tanker 79.93422 68.444962 -11.4892586
towing/pushing 91.19411 90.767121 -0.4269873

Changes in cooperation by ship category

Monterey Bay is not included in this analysis given that no data on cooperation rates during inactive VSR seasons are available.

Changes in cooperation time series

Monterey Bay is not included in this analysis given that no data on cooperation rates during inactive VSR seasons are available.

Whale presence rating and vessel compliance

Whale presence rating and VSR zone activity

Percent of data where the VSR zone was active vs. inactive, and within VSR status groupings, what the whale presence rating was. Monterey Bay is not included in this analysis as there is no whale presence rating data available.

Whale presence rating and VSR status timeseries

Whale presence rating and vessel cooperation

Percent cooperation grouped by VSR status (inactive vs. active) and whale presence rating. Here, we are only plotting cooperation data between 15-85% to remove those who never cooperate, and those who might always “cooperate” due to external factors (i.e., vessel speed capacity).

San Francisco

Southern California

Whale sightings data and vessel cooperation time series

Blue whale data streams time series

Across metrics, data points represent the year-month average for blue whales. Light grey shaded regions represent seasons when the VSR is active, while the striped regions represent when data was unavailable from the respective source.

For the acoustics panels, year-month averages were done by assigning a “Low Rating” a 1, a “Medium Rating” a 2, a “High Rating” a 3, and “offline” an NA. Then, averages were taken of these scores, and the means were plotted as they fit across the ranges of these three bins.

Proportion of days per region data was offline
Region (n = days) System Percent days offline
San Francisco (n = 846) Acoustics 56.03%
Southern California (n = 1579) Acoustics 24.64%
San Francisco (n = 846) Whale Watch 20.09%
Southern California (n = 1579) Whale Watch 11.40%

Blue whale data stream time series x year

As an example, we could also plot the data as a ridge line plot. This is presenting data across years for just the Southern California VSR zone. This plot style is repeated below and only shows data for the SoCal zone.

Correlation analysis for both zones: Confirmed whale occurrence and WhaleWatch predictions

Pearson’s

sf_corr <- wpr_join %>% filter(zone == "SF VSR")
socal_corr <- wpr_join %>% filter(zone == "Socal VSR")

#SF
cor.test(sf_corr$bwmv, sf_corr$bw_ac_score)

    Pearson's product-moment correlation

data:  sf_corr$bwmv and sf_corr$bw_ac_score
t = 45.826, df = 4283, p-value < 2.2e-16
alternative hypothesis: true correlation is not equal to 0
95 percent confidence interval:
 0.5531430 0.5933383
sample estimates:
      cor 
0.5735858 
#Socal
cor.test(socal_corr$bwmv, socal_corr$bw_ac_score)

    Pearson's product-moment correlation

data:  socal_corr$bwmv and socal_corr$bw_ac_score
t = 35.259, df = 80478, p-value < 2.2e-16
alternative hypothesis: true correlation is not equal to 0
95 percent confidence interval:
 0.1165298 0.1301373
sample estimates:
      cor 
0.1233394 

Spearman’s

#SF
cor.test(sf_corr$bwmv, sf_corr$bw_ac_score, method = "spearman")

    Spearman's rank correlation rho

data:  sf_corr$bwmv and sf_corr$bw_ac_score
S = 4472725166, p-value < 2.2e-16
alternative hypothesis: true rho is not equal to 0
sample estimates:
      rho 
0.6589084 
#Socal
cor.test(socal_corr$bwmv, socal_corr$bw_ac_score, method = "spearman")

    Spearman's rank correlation rho

data:  socal_corr$bwmv and socal_corr$bw_ac_score
S = 7.2923e+13, p-value < 2.2e-16
alternative hypothesis: true rho is not equal to 0
sample estimates:
      rho 
0.1606363 

Kendall’s

#SF
cor.test(sf_corr$bwmv, sf_corr$bw_ac_score, method = "kendall")

    Kendall's rank correlation tau

data:  sf_corr$bwmv and sf_corr$bw_ac_score
z = 43.853, p-value < 2.2e-16
alternative hypothesis: true tau is not equal to 0
sample estimates:
      tau 
0.5408426 
#Socal
cor.test(socal_corr$bwmv, socal_corr$bw_ac_score, method = "kendall")

    Kendall's rank correlation tau

data:  socal_corr$bwmv and socal_corr$bw_ac_score
z = 45.557, p-value < 2.2e-16
alternative hypothesis: true tau is not equal to 0
sample estimates:
      tau 
0.1297058 

Pearson’s

#SF
cor.test(sf_corr$bwmv, sf_corr$s_bluecount)

    Pearson's product-moment correlation

data:  sf_corr$bwmv and sf_corr$s_bluecount
t = 25.259, df = 11824, p-value < 2.2e-16
alternative hypothesis: true correlation is not equal to 0
95 percent confidence interval:
 0.2090974 0.2432993
sample estimates:
      cor 
0.2262681 
#Socal
cor.test(socal_corr$bwmv, socal_corr$s_bluecount)

    Pearson's product-moment correlation

data:  socal_corr$bwmv and socal_corr$s_bluecount
t = 36.803, df = 104622, p-value < 2.2e-16
alternative hypothesis: true correlation is not equal to 0
95 percent confidence interval:
 0.1070655 0.1190295
sample estimates:
      cor 
0.1130516 

Spearman’s

#SF
cor.test(sf_corr$bwmv, sf_corr$s_bluecount, method = "spearman")

    Spearman's rank correlation rho

data:  sf_corr$bwmv and sf_corr$s_bluecount
S = 2.0655e+11, p-value < 2.2e-16
alternative hypothesis: true rho is not equal to 0
sample estimates:
      rho 
0.2507044 
#Socal
cor.test(socal_corr$bwmv, socal_corr$s_bluecount, method = "spearman")

    Spearman's rank correlation rho

data:  socal_corr$bwmv and socal_corr$s_bluecount
S = 1.635e+14, p-value < 2.2e-16
alternative hypothesis: true rho is not equal to 0
sample estimates:
      rho 
0.1434296 

Kendall’s

#SF
cor.test(sf_corr$bwmv, sf_corr$s_bluecount, method = "kendall")

    Kendall's rank correlation tau

data:  sf_corr$bwmv and sf_corr$s_bluecount
z = 27.384, p-value < 2.2e-16
alternative hypothesis: true tau is not equal to 0
sample estimates:
      tau 
0.2070631 
#Socal
cor.test(socal_corr$bwmv, socal_corr$s_bluecount, method = "kendall")

    Kendall's rank correlation tau

data:  socal_corr$bwmv and socal_corr$s_bluecount
z = 46.445, p-value < 2.2e-16
alternative hypothesis: true tau is not equal to 0
sample estimates:
      tau 
0.1170324 
Acoustics & WhaleWatch Correlation
Correlation Method Correlation metric
San Francisco
bw_ac_score~bwmv pearson 0.5735858
bw_ac_score~bwmv kendall 0.5408426
bw_ac_score~bwmv spearman 0.6589084
Southern California
bw_ac_score~bwmv pearson 0.1233394
bw_ac_score~bwmv kendall 0.1297058
bw_ac_score~bwmv spearman 0.1606363
Sightings & WhaleWatch Correlation
Correlation Method Correlation metric
San Francisco
s_bluecount~bwmv pearson 0.2262681
s_bluecount~bwmv kendall 0.2070631
s_bluecount~bwmv spearman 0.2507044
Southern California
s_bluecount~bwmv pearson 0.1130516
s_bluecount~bwmv kendall 0.1170324
s_bluecount~bwmv spearman 0.1434296